Located in South America, primarily in Brazil, the Amazon River is the world's largest river by volume. Its water flow is greater than the combined flow of the next six largest rivers. It was formerly thought to be also the longest river in the world, but is now believed to be slightly shorter than the River Nile.

The Amazon River is so vast that is sometimes called The River Sea. During the rainy season the Amazon can be up to 24.8 miles wide. It is so wide that it is not always possible to see across it to the other side. It is navigable all year round, by sea-going vessels as far up as the port of Iquitos in Peru.

The Amazon, its tributaries, and the surrounding Amazonian rain-forest, are inhabited by a greater diversity of animal and plant life than anywhere else on Earth.

In H. G. Wells' novelThe History of Mr. Polly, the title character loves to read about exotic places. The Amazon was one place that captured his imagination, "but when he discovered that you could not see one bank from the other, he lost, through some mysterious action of the soul that again I cannot understand, at least a tithe of the pleasure he had taken in that river."